I have tried every format that is known to Screensaver Factory 4 and I can't get any of them to play. I'm using the demo version to decide if this is the program I want to use.
I've had two manifestations of this problem:
1) The computer did not have Windows Media player 9 installed. Installing WMP 9 fixed the not playing on the developemnt machine problem.
2) We made several movies into screen savers that the dev machine could play but would not play on the test machine. The problem turned out to be that the movie itself was using a codec not found on the test machine (DivX). so by rencoding the movie to use a more popular codec (WMP 7) we solved the problem.
A very usefull tool for determing what codec a given movie is encoded with is called gspot
http://www.headbands.com/gspot/
hth,
Sam S.